Downloading and Reposting an Image in Node.js

Question

Use case: Download a short-term expiring profile image from URL, and re-post it to my own server for long-term hosting.

First, I download the image data to a string:

const request = require('request-promise');

const img_data = await request(soon_to_expire_url);

I've got a string with binary data now. Now what? Convert it to base64? to a blob? to a stream of some sort?

Next, I need to post the downloaded image to an API for long-term hosting, using axios. The problem is I can only get it work with fs.createReadStream, which requires a file path, not a data string.

const axios = require('axios');
const FormData = require('form-data');


    var data = new FormData();
    data.append('user_id', user_id);
    data.append('profile_file', fs.createReadStream('non-existing-file.jpg'));
    
    var config = {
      method: 'POST',
      url: 'serverEndpoint',
      headers: { 
        'Content-Type': 'application/json', 
        ...data.getHeaders()
      },
      data : data
    };
    
    return axios(config)
    .then(function (response) {
      console.log(JSON.stringify(response.data));
    })

So how can bridge the gap? How can I create something out of the downloaded image that then takes the form of whatever createReadStream produces?

I've tried reducing it to a base64 string starting with data:image/jpeg;base64,..., but that doesn't take.

Last resort would be saving the image to a temp file, then posting that file path, but I would rather avoid that.

Answer 1

Either way you have to store the file somewhere anyway.

You can try something like this

let file = null;
async function decodeBase64(base64String){
fetch(base64String)
  .then(res => res.blob())
  .then(blob => {
     file = new File([blob], "temp",{ type: "image/png" })
  })
}
await decodeBase64(base64String)

  var data = new FormData();
    data.append('user_id', user_id);
    data.append('profile_file', file));